So as many new people come to MIUI wonder the same way I did, how do I get a Full Screen Calling ID for contacts?
It’s easy to do, but you gave to set pictures for each person individually one-by-one.
First select the contact you want and press edit, then scroll to the bottom.
Select Edit (Add) Photo
Select from Gallery or Take a Photo
Once you got the image you want use 2 fingers to zoom in and out, move it how you want it (you can rotate by press top corners).
Press use photo then save contact changes.